lec 6 Flashcards
morphological species concept
- members of some species look very different
2. different species may look very similar
reproductive isolation
organisms able to successfully reproduce amongst themselves should be considered a species
Biological species concept
interbreeding is sharing a common gene pool and producing fertile offspring
Ecological species concept
A species is a group of phonetically similar organisms that occupy a given niche
(but how do you define a niche?)
species integrity maintained by adaptation to a certain niche (hybrids not viable because their not as successful as their parents)
barriers to inbreeding between species
pre-zygotic reproductive barriers
post-zygotic reproductive barriers
Pre-zygotic reproductive barriers
Prevents mating or fertilization
Post-zygotic reproductive barriers
prevent development of fertile adults
Habitat isolation
species in different habitats don’t connect with each other (pre-zygotic)
temporal isolation
species have different reproductive timing or become sexually mature at different times in the year, (pre-zygotic)
behavioural isolation
There is little or no sexual attraction between males and females of different species due to differences in behaviour or physiology
Mechanical isolation
structural differences in reproductive anatomy prevent copulation between two different species
gamete isolation
male and female gamete die before uniting or fail to unite
Hybrid non-viability
Hybrid zygotes fail to develop or to reach sexual maturity (post-zygotic)
hybrid sterility
hybrid fail to produce functional gametes (post-zygotic)
hybrid breakdown
hybrid species are initially successful but subsequent hybrids become weaker over time (post-zygotic)
